Synthesis and optical studies of Y-shaped imidazole derivatives.

A novel series Y-shaped π-expanded imidazole based chromophores was designed and synthesized. The series contains thirteen 2-aryl-4,5-bis[2-(aryl)vinyl)]-1H-imidazoles (6a-6m), which were characterized by spectroscopic analysis. The structures of compounds 6d and 6j were also confirmed by X-ray crystallographic analysis. The optical studies were investigated using absorption and emission measurements in dichloromethane. The fluorescence quantum yields were observed varying in 0.22-0.59 range, but the compounds with nitro substituent did not show the fluorescence. The absorption and emission study of the series helped us to understand the effect of substituents on the optical properties of compounds as well.